1. Field of the Invention
The present invention relates to valves and more particularly relates to cargo valves as used between horizontal bulkheads on for example barges.
2. General Background and Prior Art
There is presently existing in this country a severe energy crisis which is due in part to the ever increasing rise in the cost of sources of energy such as fossil fuels, oil, gas and the like.
An apparent future solution to at least a portion of this problem is the use of coal as a source of energy.
Coal can be transmitted through pipe-lines when it is shipped in the form of a slurry (i.e. mixed with a liquid such as water for example). Such slurries can loaded dry be pumped through a pipe-line much in the same way as any other liquid material. This will allow the transmission of coal and ores from central United States and western sites to eastern and southern electrical plants and refineries.
Barges can also be used for the transportation of dry bulk materials which will be loaded dry through chutes or by conveyor and then fluidized by air to be discharged. Included in this group are several grain products for example.
The pumping of slurry materials using pneumatic pumping is discussed in my prior patent U.S. Pat. No. 3,883,269 issued May 13, 1975 and entitled "Liquid Transfer System".
One of the problems in the pumping of slurried materials is the wear which is experienced by the pump itself and any inner working parts. The same abrasion problem exists in the inner workings of valves which are used to control the flow of slurried materials during transfer to an from barges and the like.
Many cargo pumps have been patented. Some prior art patents of which I am aware are below discussed.
A cargo or gate valve for hopper cars or the like is seen in U.S. Pat. No. 3,556,469. In that patent there is provided a hand wheel which operates a vertical shaft attached at its lower end portion to a pyramid shaped valving member. The valving member opens and closes a lower discharge opening. Guide rods are provided to insure that the pyramid valve member will not be permitted to rotate during operation of the gate valve.
A valve for controlling the discharge of plastic or semi-solid material particularly from tank mixers and the like is seen in U.S. Pat. No. 1,681,209.
A loading and unloading valve adapted to be mounted in the bottom of a tank is seen in U.S. Pat. No. 4,194,523. A valve sealing a lower outlet opening in a tank for example is seen in U.S. Pat. No. 4,176,821.
U.S. Pat. No. 4,011,885 shows a manifold valve structure for use with a multi-compartmented transportation tank for liquids, such as for instance a mobile gasoline or oil transportation tank. The valve is actuated by means of a hand wheel which rises an elongated vertical stem and an associated valve disc with the disc being raised to a desired elevation.
The prior art type valves suffer in that do not provide a simple and economical means for the discharge of fluid such as slurries, bulk cargo and the like from tanks through a lower horizontal gravity flow discharge opening.
One problem in the control of bulk cargo and abrasive cargo such as slurries, grain, and the like is that abrasion and wear and friction is much greater than with liquid cargo. Thus, prior art type valves which are exposed to the discharge stream are prematurely worn out. Many gate valves and like controllers are ineffective in controlling the discharge of bulk materials from tanks because the discharge area is too highly restrictive and a less than optimum flow rate is seen. Many prior art type valves are complex and expensive to manufacture and difficult to maintain.
A further problem in the control of discharge flow from tanks especially in the discharge of slurry materials, viscous materials, grain and the like is the precise control of the quantity of flow which leaves the tank. In a multi-tank vessel such as a barge for example, it is desirable to discharge the tanks in a sequence which insures a proper head on the discharge flow lines at all times.